A Microsoft application for managing email, calendars, contacts, and tasks across devices and platforms.
Something to check that I saw on another case today.
In Outlook click File, Account Settings, Account Settings. Click Data Files. Locate the Data File for your PST file and double click to see the properties. Where it shows the File Name is the format similar to C:\Users\username\Documents\Outlook Files\filename.pst. In the case we had today the path was something like "\?\C:\documents\test.pst".
If you see it with the wrong path you can click the Email tab and click the POP account and then click Change Folder, New Outlook Data File, and choose the original PST it is using to update the path.
Aside from this issue I am not seeing other reports yet. It would be helpful if the above does not apply to try creating a new Outlook profile and see if the POP account search will work in that profile.